Effect of temperature on toxicity of pyrethroids and endosulfan, activity of mitochondrial Na-K-ATPase and Ca-Mg-ATPase in Chilo suppressalis (Walker) (Lepidoptera: Pyralidae)

The toxicity of deltamethrin, bifenthrin, and endosulfan to the fourth-instar larvae of rice stem borer, Chilo suppressalis (Walker), was measured at 17, 27, and 37 °C. The three insecticides all displayed a positive temperature coefficient between 17 and 37 °C. The temperature coefficients of deltamethrin, bifenthrin, and endosulfan were 5.59, 1.68, and 2.85, respectively. However, temperature coefficients of deltamethrin and bifenthrin between 17 and 27 °C and between 27 and 37 °C varied. The inhibition of the above three insecticides to mitochondrial Na⁺-K⁺-ATPase and Ca²⁺-Mg²⁺-ATPase from the fourth-instar larvae of rice stem borer was determined at 17, 27, and 37 °C. The inhibition of deltamethrin to the specific activities of Na⁺-K⁺-ATPase and Ca²⁺-Mg²⁺-ATPase showed a negative temperature coefficient, but endosulfan exhibited a positive temperature coefficient. Inhibition of bifenthrin exhibited the contrary temperature coefficients between Na⁺-K⁺-ATPase and Ca²⁺-Mg²⁺-ATPase and a negative temperature coefficient for the former and a positive temperature coefficient for the later.